This application claims priority of German Application No. 199 21 092.6-23 filed Apr. 30, 1999, a copy of which is Attachment A hereto, the disclosure of which is incorporated fully herein by reference.
The invention relates to a method for standardizing the pane position of an external force actuated vehicle window lifter.
Standardizing the pane position is of particular importance in the case of vehicle window lifters which are fitted with a device for detecting a jammed object. With these window lifters the drive is automatically switched off and where necessary reversed when the window pane during its upward movement strikes an obstruction which would otherwise be clamped between the upper edge of the pane and the window frame.
However there is a problem here in that the movement of the window pane into the upper pane seal could be interpreted as a jamming case on account of the resistance exerted by the pane seal against the displacement movement of the window pane. The window lifter would then be automatically switched off and the window pane could not then be moved completely into the upper pane seal. To solve this problem various proposals have been put forward in order to deactivate the anti-jam protection as the window pane enters into the upper pane seal, see here DE 196 28 203 C1. However in order to be able to do this it is necessary to determine accurately the relevant position of the window pane during its displacement movement.
For these reasons it is customary prior to initially operating an external force actuated window lifter or even after its repair to move the window pane once into its closed position in order to standardize the pane position. This upper end position of the window pane then serves as a zero or reference position for the window pane, in relation to which all individual displaced positions of the window pane can be determined along its displacement path.
In view of the importance of standardizing the pane position for a satisfactory functioning of an anti-jam protection system and furthermore in general for a reliable detection of the actual position of a displaceable window pane it is absolutely crucial to eliminate faults as far as possible when standardizing the pane position. For faults in the standardizing of the pane position can lead for example to a jamming case which occurs as the window pane is raised being misinterpreted by the anti-jam protection system as the window pane moving into the upper pane seal. The result of this would be that the drive of the window lifter is not switched off but rather is operated further with an increased current supply so that the resistance of the supposed pane seal can be overcome. This can lead to serious injury particularly in the case where part of the body is jammed.
The object of the invention is to provide a method for standardizing the pane position of a window lifter wherein a faulty standardizing of the pane position is reliably eliminated as far as possible.
According to this in order to check whether the window pane during standardizing has properly reached its upper end position (closed position), the change is evaluated in a value correlated with the dynamics of the window pane as the window pane enters into the seal area associated with the closed position.
The invention is based on the knowledge that the dynamics of the window pane when entering into the pane seal associated with the closed position is influenced in a characteristic way. Therefore by taking into account the dynamics of the window pane it can be readily checked whether the window pane has actually properly entered into the upper sealing area. More particularly it can be reliably established whether during standardizing of the pane position the entrance of the window pane into the closed position is prevented through a faulty fitting of the window lifter or through an object jammed between the window pane and the seal area. In the latter case the end position reached during standardizing the pane position is recognised as a position not corresponding to the actual closed position and therefore is not used consequently as the reference or zero point position of the window pane.
The failed standardizing can be indicated through an optical or acoustic signal. Furthermore after a failed standardizing the automatic function of the external force actuated window lifter is not activated, that is for as long as no proper standardizing of the pane position has been completed the window lifter cannot be moved automatically into its upper end position.
In particular the period length or speed of the drive (or of a displacement element connected with the drive, such as for example a gear part of the window lifter or the window pane itself), the current collection of the drive or the change of speed (acceleration) or change of current collection, can all be considered as values correlated with the dynamics of the window pane which can be used to check whether the window pane has reached its end position in the upper seal area. Basically when carrying out the method according to the invention any value can be used which reflects the influence of the upper pane seal on the dynamics of the window pane.
The entrance of the window pane into the seal area can be detected in particular from a local extremum of the value correlated with the dynamics, preferably the speed or period length, in dependence on the displacement site of the window pane. Thus when the window pane enters into the seal area there is normally at first a drop in the speed or an increase in the period length of the drive. After the window pane has moved by its leading upper edge a little further into the seal area however and has thereby overcome the resistance of the sealing lip of the seal area pressing against the window pane, a certain increase in the speed or decrease in the period length of the drive occurs again. A local minimum or local maximum respectively is hereby formed in the path of the speed or of the period length of the drive over the displacement path of the window pane. This is typical for the upper edge of the window pane entering into the seal area and can thus be used as a typical criterion for reaching the closed position of the window pane. If however the window pane during standardizing strikes an obstruction by its leading edge then the speed is decreased or the period length increased substantially continuously. It does not result in forming an extremum. The entrance into the seal area can thereby be clearly differentiated from striking an obstruction of another kind.
When evaluating the value correlated with the dynamics of the window pane not only should the actual displacement position of the window pane be used, but also where applicable some pre-values of the value correlated with the dynamics of the window pane. This prevents the result of the evaluation from being falsified by environmental factors, wear etc.
In a preferred embodiment of the invention the standardizing of the pane position is interrupted when after a predeterminable time span no path of the value correlated with the dynamics of the window pane has been observed which is characteristic of the entrance of the window pane into the seal area. This then signifies that during standardizing of the window pane no proper displacement movement of the window pane is taking place and thus a reliable standardizing of the pane position cannot be carried out.
Furthermore standardizing the pane position is preferably then only carried out when the window pane has moved at least along a path length which is greater than the extension of the pane seal in the direction of movement of the window pane. For only in such a case is it ensured that the characteristic behaviour of the value correlated with the dynamics of the window pane which appears as the leading edge of the window pane enters into the seal area can actually be observed. Advantageously the minimum displacement path of the window pane is thereby selected slightly larger than the extension of the seal area in order to ensure that the window pane when entering the seal area has already reached its usual displacement speed (swung-in system state).